Overview
Landing gear is the undercarriage of an aircraft or spacecraft used to support it while parking, taxiing, taking off, and landing, engaging either land or, in the case of seaplanes, water. Landing gear forms a foundational part of the airframe, supporting the aircraft's full weight while on the ground and keeping the fuselage elevated enough to avoid frictional or collision damage during ground operations. Wheeled landing gear is by far the most common configuration on modern aircraft, though skis, floats, and skids are used on aircraft designed to operate from snow, water, or unprepared surfaces respectively. Retractable landing gear, which folds into the fuselage or wings during flight to reduce drag, became standard on higher-performance aircraft as speeds increased, while many smaller general aviation aircraft retain simpler fixed gear for cost and mechanical simplicity.
History
Early aircraft used simple fixed landing gear, often little more than wheels or skids mounted directly to the airframe, since low speeds and light weights made retraction unnecessary. Retractable landing gear began appearing in the 1930s as aircraft speeds increased and the drag penalty of fixed gear became significant enough to justify the added mechanical complexity of a retraction system. Hydraulic retraction systems became standard on larger aircraft through the mid-20th century, and modern airliners now rely on sophisticated hydraulic and electronic systems to manage gear extension, retraction, and steering. Despite these advances, many smaller general aviation aircraft have retained simple fixed gear into the present day, since the weight and cost savings often outweigh the modest drag penalty at their lower operating speeds.
Design & Specifications
Landing gear assemblies include shock-absorbing struts, wheels, brakes, and on larger aircraft, retraction mechanisms folding the gear into the fuselage or wings.
Operations
Pilots extend landing gear before landing and retract it after takeoff, with hydraulic or electric systems managing the extension and locking sequence.
References
| Category | Aerodynamics & Aircraft Anatomy |
| Type | Aircraft undercarriage |
| Common Config | Wheeled (also ski/float/skid) |
| Retractable Origin | 1930s |
| Function | Ground support + shock absorption |